ED Sciences et environnements
COVARIATION BETWEEN LOADING ENVIRONMENT AND MANDIBULAR CORTICAL BONE DISTRIBUTION IN MODERN HUMANS
by Pierre-Hadrien DECAUP (De la Préhistoire à l'Actuel : Culture, Environnement, Anthropologie)
The defense will take place at 14h00 - L'amphithéâtre GAMA bâtiment A33, le Campus Peixotto, Avenue de la Libération - rue Pierre Noailles - 33400 Talence.
in front of the jury composed of
- Christine VESCHAMBRE-COUTURE - Professeure des universités - Université de Bordeaux - UMR 5199 PACEA - Directeur de these
- Rémi ESCLASSAN - Professeur des universités - praticien hospitalier - Université d'Aix-Marseille - UMR 7268 ADES - Rapporteur
- Jean-Jacques HUBLIN - Professeur des universités - Max Planck Institute for Evolutionary Anthropology - Examinateur
- Elsa GAROT - Professeure des universités - praticienne hospitalière - Université de Bordeaux - UMR 5199 PACEA - CoDirecteur de these
- Asier GÓMEZ-OLIVEIRA - Professeur - Euskal Herriko Unibertsitatea - Rapporteur
- Jean-Christophe FRICAIN - Professeur des universités - praticien hospitalier - Université de Bordeaux - UMR 1026 BIOTIS - Examinateur
As the moving element of the manducatory system, the human mandible is central to the functions of ventilation, swallowing, mastication, prehension and phonation, and therefore must withstand complex loads of varying intensity and frequency. Although the morpho-functional interactions between this loading environment and the external human mandibular shape have been partially documented, the morpho-functional approach to internal mandibular bone anatomy remains unclear. Some authors, such as Demes et al. (1984) have postulated that this morpho-functional relationship could be based on a faciolingual asymmetry. In this context, the aim of the present work is to question the ‘mechanistic' paradigm of Demes et al. (1984) considering new methodological approaches and thus answer the following question: ‘Does the distribution of mandibular cortical bone covary with the loading environment in modern humans?'. Through a systematic review of the literature (Decaup et al., 2023), a comparative morphometric approach within past populations (Decaup et al., 2024a) and modelling of this problem using the finite element method (Decaup et al., 2024b, under review) we found that the distribution of mandibular cortical bone covaries, under certain conditions, with the distribution of strain in unilateral molar masticatory loading conditions. Morphological effects of this covariation are particularly marked in human groups with a high level of mandibular load. Finally, this covariation follows an anteroposterior gradient towards a weaker relationship in the symphyseal anterior regions and a stronger relationship in the posterior regions of the mandibular corpus. The development of an approach combining comparative morphometric analysis and finite element analysis in global-local modelling could provide a better interpretation of the biomechanical impact of the biological diversity of mandibular cortical bone distribution within human populations in future research.